Microorganisms can live and proliferate as individual cells swimming freely in the environment (e.g., plankton), or they can grow as highly organized, multicellular communities encased in a self-produced polymeric matrix in close association with surfaces and interfaces. The latter microbial lifestyle is referred to as biofilms. Biofilm formation represents an ancient, protected mode of growth that allows microbial survival in hostile environments and allows microorganisms to disperse and colonize new niches [Hall-Stoodley et al., Nat Rev Microbiol. (2004) 2(2):95-108]. The composition of biofilms is complex and variable among different microbial species and even within the same species under different environmental conditions. Nonetheless, biofilm formation represents the normal lifestyle of microorganism in the environment and all microbes can make biofilms. Previous studies revealed that bacterial biofilm formation progresses through multiple developmental stages differing in protein profiles [Sauer et al, J Bacteriol. (2002) 184(4): 1140-54], beginning with attachment to surface, followed by the immigration and division to form microcolonies and finally maturation involving expression of matrix polymers. Bacteria within each biofilm stage display phenotypes and possess properties that are markedly different from those of the same group growing planktonically [Sauer et al., J Bacteriol. (2004) 186(21):7312-26]. Biofilms are a major cause of systemic infections (e.g., nosocomial infections) in humans.
The composition of biofilms is complex and variable among different microbial species and even within the same species under different environmental conditions. Nonetheless, biofilm formation represents the normal lifestyle of microorganism in the environment and all microbes can make biofilms. Previous studies revealed that bacterial biofilm formation progresses through multiple developmental stages differing in protein profiles [Sauer et al., J Bacteriol. (2002) 184(4): 1140-54], beginning with attachment to surface, followed by the immigration and division to form microcolonies and finally maturation involving expression of matrix polymers. Bacteria within each biofilm stage display phenotypes and possess properties that are markedly different from those of the same group growing planktonically [Sauer et al., J Bacteriol. (2004) 186(21):7312-26].
In the body, biofilms can be associated with tissues (e.g., inner ears, teeth, gums, lungs, heart valves and the urogenital tract) and can be a major source of systemic infections. An estimated 65% of bacterial infections in humans are biofilm in nature. Additionally, after forming biofilms, microorganisms tend to change their characteristics, sometimes drastically, such that doses of antibiotics which normally kill the organisms in suspended cultures are completely ineffective against the same microorganisms when the organisms are in attached or conglomerate biofilm form. See U.S. Pat. No. 7,189,351, incorporated by reference in its entirety.
One of the principal concerns with respect to products that are introduced into the body (e.g., contact lenses, central venous catheters, mechanical heart valves and pacemakers) or provide a pathway into the body is microbial infection and invariably biofilm formation. As these infections are difficult to treat with antibiotics, removal of the device is often necessitated, which is traumatic to the patient and increases the medical cost. PCT Application No. WO 06/006172 discloses the use of anti-amyloid agents, such as aromatic compounds, for inhibiting formation or disintegrating a pre existing biofilm. The application discloses that compounds preventing amyloid fibril formation in Alzheimers can act against fibril formation in biofilms, and concludes that amino acids having an aromatic arm are effective against biofilms. However, the analysis was limited to full length sequences.
Biofilms can cause, amongst a wide range of negative effects, accelerated corrosion in industrial systems, oil souring and biofouling. Bacterial aggregation can occur in agriculture [Monier et al., Applied and Environmental Microbiology, 70(1): 346-355 (2004); Biofilms in the food and beverage industries, Edited by P M Fratamico, B A Annous and N W Guenther, USDA ARS, USA, Woodhead Publishing Series in Food Science, Technology and Nutrition No. 181, Chapter 20, pages 517-535] and in water systems [Carlson et al., Zentralbl Bakteriol Orig B, 161(3): 233-247 (1975)]. Biofouling may be caused by the adhesion of organisms to any surface in a marine or freshwater environment, including cooling towers, water pipes and filters in cooling or desalinization installations, irrigation and power stations, and membranes, such as those used in wastewater and desalinization systems. Biofouling also occurs in aquaculture systems in fish farms. Furthermore the commercial shipping fleets of the world consume approximately 300 million tons of fuel annually. Without antifouling measures, that fuel consumption would increase by as much as 40%, equivalent to an extra 120 million tonnes of fuel annually. The economic cost of this was estimated as about $7.5 billion in 2000; a more recent estimate is $30 billion. Generally, biofilms are very difficult to eliminate since microbes growing within are highly organized and can withstand hostile environments, such as high temperatures and anti-microbial agents (e.g., antibiotics).
Since marine-aquatic plants and animals are continuously exposed to a large diversity and abundance of potentially harmful microorganisms in the form of biofilm, and it is known that marine life produce anti-microbial peptides, it is possible that broad spectrum natural factors that interfere with biofilm formation may also be present in marine life.
U.S. Publication No. 20070098745 discloses means of preventing biofilm formation by the use of reef fish microflora. This invention describes anti-biofilm substances derived from bacteria isolated from the epithelial mucosal surfaces of healthy coral reef fish (e.g., Sparisoma ninidae and Lutjanus purpureus). The bacterial isolates produce signals or toxins that prevent biofilm formation.
Cell clustering is not limited to microbial biofilms, but can exist in vivo. Alzheimer's Disease, for example, involves neuron clusters (i.e., neuritic plaques) in the brain [Tiraboschi et al., J. Neurology, 62(11): 1984-1989 (2004)]. In the body, bacterial aggregation can occur orally [Duffau et al., 16 Sep. 2005 RAI Congress, #0299; Liljemark et al., Infect. Immun., 31(3): 935-941 (1981)]; in sepsis [Reid et al., Current Microbiology, 20(3): 185-190 (1990)]; diarrhea [Bieber et al., Science, 280(5372): 2114-2118 (1998)]; in nosocomial infections [Bortz et al., Bulletin of Mathematical Biology, Volume 70, Number 3, 745-768]; in relation to drug efficacy [Kraal et al., J Dent Res 58(11): 2125-2131 (1979)]; in relation to peritoneal dialysis [Reid et al., Peritoneal Dialysis International, 10: 21-24 (1990)]; lung diseases [Sanchez et al., PLoS Pathog 6(8)]; and Crohn's disease [Isenmann et al., Digestive Diseases and Sciences, 47(2): 462-468 (2002)].
Cell clustering can also occur among white blood cells in vivo. For example, white blood cells can aggregate in whole blood as the result of cigarette smoking and lead to microvascular occlusion and damage [Hill et al., J. R. Soc. Med., 86(3):139-140 (1993)]. White blood cell aggregation can also occur in vascular disease [Belch et al., Thrombosis Research, 48(6):631-639 (1987)]. Macrophage-lymphocyte clustering is correlated to rheumatoid arthritis [Webb et al., Macrophage-lymphocyte clustering in rheumatoid arthritis, Ann. rheum. Dis. (1975), 34, 38] Additionally, Sun et al. state, “Both platelet aggregation and white blood cell aggregation are involved in pathological processes such as thrombosis, atherosclerosis and chronic inflammation. People in older age groups are likely to suffer from cardiovascular diseases and may have increased white cell and platelet aggregation which could contribute to this increased risk.” [Sun et al., A study of whole blood platelet and white cell aggregation using a laser flow aggregometer, Platelets (2003) March 14(2):103-8.] Furthermore, adhesion and aggregation of white blood cells are involved in vascular diseases and thrombosis [Belch et al., Whole blood white cell aggregation: a novel technique, Thrombosis Research, 48; 631-639 (1987)].
Cell clustering also occurs in restenosis, which can develop as the result of implanted medical stents [Dangas et al., Circulation, 105:2586 (2005)]. Such clustering can lead to the occlusion of a blood vessel and dramatically reduced blood flow. One of the symptoms of the second stage of restenosis, which tends to occur 3-6 months after surgery, is platelet aggregation at the site of the injury [Michael Kirchengast*, Klaus Munter. Endothelin and restenosis. Cardiovascular Research 39 (1998) 550-555] and residual plaque burden outside the stent [Prati et al., In-Stent Neointimal Proliferation Correlates With the Amount of Residual Plaque Burden Outside the Stent. An Intravascular Ultrasound Study, Circulation, (1999) 99:1011-1014.], both phenomena being the main causes of in-stent neointimal proliferation. Patri et al concludes with the following: “Late in-stent neointimal proliferation has a direct correlation with the amount of residual plaque burden after coronary stent implantation, supporting the hypothesis that plaque removal before stent implantation may reduce restenosis.”